Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Ch 5 Lecture Notes
Document related concepts
Soil respiration wikipedia , lookup
Soil horizon wikipedia , lookup
Crop rotation wikipedia , lookup
Terra preta wikipedia , lookup
Soil food web wikipedia , lookup
Soil compaction (agriculture) wikipedia , lookup
No-till farming wikipedia , lookup
Soil erosion wikipedia , lookup
Surface runoff wikipedia , lookup
Canadian system of soil classification wikipedia , lookup
Soil salinity control wikipedia , lookup
Soil microbiology wikipedia , lookup
Transcript
! Any rock projects planned?! ! 1 Steak = 4 tons of weathered rock! I dont’ know. I just like this guy. WEATHERING & SOIL Where would we be without weathering?! ! Without erosion? PRETTY PICTURE Where did that stuff under the rock come from?! What is happening to the rock? ! What are the green and red things?! Why is the rock rounded rather than square? Why is this water red? Types of Weathering! ! A) Mechanical / Physical - Breaking the rock or mineral.! ! B) Chemical - Altering the molecules of the rock or mineral.! ! Mechanical/Physical! Weathering Mechanical Weathering - Exfoliation Types of Mechanical Weathering! ! A) Exfoliation! B) Pressure Release! C) Ice - Frost Action / Frost Heaving / Ice Wedging (Talus)! D) Root Pry! E) Salt Spalling! Mechanical Weathering - Exfoliation Mechanical Weathering - Exfoliation Sheet Joints - Occurrs often in granite due to pressure release.! Mechanical Weathering - Exfoliation Mechanical Weathering - Exfoliation! ! Exfoliation Dome, Half Dome, Yosemite Mechanical Weathering - Some Mystery Place Mechanical Weathering - Exfoliation! ! Stone Mountain Georgia Potential for fun rock slides. :) Mechanical Weathering - Exfoliaion Mechanical Weathering - Pressure Release & Exfoliation Glaciers contribute to this.! Also known as ‘spalling’.! Good for fun rock slides! :) Frost Action Most substances contract ! when frozen. Think of a balloon on a! cold day. Brrr.... Frost Wedging - Strangely, water expands 9% ! when freezing. Silicon, antimony, bismuth and gallium all also expand. Mechanical Weathering - Formation of Talus TALUS Talus - Sierras No Talus - Picacho Peak ! ! Why? Frost Heaving - Mount Kenya Ice Wedging - Potholes Mechanical Weathering ! Frost Heaving - Not Mount Kenya Mechanical Weathering - Root Pry! ! This MUST be stopped! ! Visit ! www.respecttherock.com ! Mechanical Weathering - Lichens Mechanical Weathering - Salt Spalling Granite Tor Mechanical - Spheroidal Weathering Granite Tors The slow cooling of granite containing radioactive minerals maintains the temperature within, producing large crystals. A layer cooled and formed a cap which trapped molten magma with volatile gases and hydrothermal liquids beneath. Gases escaped through joints and fissures to the surface, rotting the granite in areas, weakening the granite as it altered minerals to secondary forms. Mechanical - Thermal Expansion and Contraction CHEMICAL WEATHERING Types of Chemical Weathering! ! A) Oxidation! B) Acids (Roots)! C) Hydration! D) Root Pry! E) Salt Spalling! Chemical Weathering! ! Decomposition due to exposure to ! water, CO2, and more.! ! Minerals like olivine that form where! there is no water may readily bond with ! water when exposed - vapor or liquid.! ! Minerals that form in the ! absence of oxygen... Did we REALLY just look at 20 slides of rocks breaking? This guy needs a LIFE! Chemical Weathering - Oxidation Hematite - Polished and Natural 4 Fe + 3O2 -> 2Fe2O3! iron oxygen hm....! The Role of Oxygen Chemical Weathering - Hydration Hematite + Water = Limonite! ! Hematite can be extracted ! from mining tailings but not! limonite. Why?! Acid Rain! &! Weathering I’m melting....... Acid rain, seriously? I mean REALLY? I’m melting...! Example - Cleopatra’s Needle - 3100 years in Egypt, no problem. 68’ X 180 tons of red granite. First built in 1450 BC. Inscriptions added by some slow tagger about 200 years later. Moved to NYC, London, Paris in 1881. Let’s Make Our Own Cleopatra’s Needle! ! Okay, boys and girls, let’s start with a piece of chalk, a paper clip, a beaker and some vinegar...! ! http://scienceboom.com/112/scienceboom-episode-4-chemical-weathering.htm! ! How is this demonstration accurate? Inaccurate? (It isn’t really fair!)! ! Did we REALLY just look at 20 slides of rocks breaking? This guy needs a LIFE! Chemical Weathering - Acid Rain Soil CO2 (10%) is much stronger than atmospheric CO2 (0.03%). ! ! Acid Rain... H20 + CO2 -> H2CO3 (Water + CO2 -> Carbonic Acid)! H2CO3 + CaCO3 -> Ca + 2HCO3! ! Human emissions of CO2 ! are 95-98% of total. Chemical Weathering - The Effect of Carbonic Acid? Chemical Weathering - Acids & Acid Rain, Vog ! ! H2CO3 + CaCO3 -> Ca + 2HCO3! http://earthobservatory.nasa.gov/IOTD/view.php? id=82071&src=eoa-iotd The Lazio region of central Italy has many landforms of volcanic origin, including several large lakes that mark the locations of ancient volcanoes. This photograph from an astronaut on the International Space Station highlights two such lakes—Lago di Vico and Lago Bracciano—located to the northwest of Rome. Chemical Weathering Slate vs. http://earthobservatory.nasa.gov/IOTD/view.php? id=82071&src=eoa-iotd Chemical Weathering - The Effect of Oxidation (Rusting) Marble Chemical Weathering - Desert Varnish A major part of varnish is clay, deposited by wind. Clay acts as a substrate to catch additional substances that chemically react together when the rock reaches high temperatures in the desert sun. Wetting by dew is also important in the process.! Another important characteristic of desert varnish is that it has an unusually high concentration of manganese. Manganese is relatively rare in the Earth's crust, making up only 0.12% of its weight. In desert varnish, however, manganese is 50 to 60 times more abundant. This significant enrichment is thought to be cause biochemical processes since many species of bacteria use manganese.! Chemical Weathering - Feldspar FELDSPAR=>CLAY (AL 2 SI 2 O 5 (OH) 4 ) ! AND SOME SILICA AND IONS. What DOESN’T WEATHER?! The more mechanical weathering, the faster it goes. ! ! ! Why do we grind coffee beans?! ! And what does this have to do with weathering? Can you define the relationship between grain size ! and surface area?! Mechanical - Spheroidal Weathering WEATHERING OF GRANITE AND SCHIST AND GNEISS C’mon, did you really think that was it for feldspar? Differential Weathering A B Chemical Weathering - Diamonds - Woohoo! Real Life Geologic Problem! ! You have a rock you love. It loves to be outside. Where will you put your beloved rock to preserve it for the longest possible time? ! ! ! ! Respect the rocks!! ! SOIL So how deep is the soil in our area? Depth to Bedrock Text Watching soil form exciting!! Become popular.! Set up a soil-forming-watching party with your friends!* Soils! ! Where do soils come from?! - Residual! - Transported! ! Variability! Regolith - all rock! ! Composition?! Sandy?! Silty?! Clayey? (?)! Loamy? (= sand, silt, clay) *They might become former friends quickly. SOILS ! Caliche - Hardpan - Mineral rich water being LIFTED. Weird... Factors Affecting Soil Formation! ! Parent Material - Residual Soils ! Volcanic soil - Hawaii! Clay soils - Colorado Plateau (get ready to dust!)! Sandy soils - McDowells! ! Climate - ! ! Slope - Steeper = less (becomes transported! ! Critters/Plants - More critters, more organic material! ! Time! Young soil vs. Mature soil (Allowed to watch “Joe Dirt”)! Layers of soil over alternating basalt RESIDUAL & TRANSPORTED SOILS SOIL TYPES Crazy Aussie Soil Scientists! Soil Erosion SOIL EROSION ! ! "The threat of nuclear weapons and man's ability to destroy the environment are really alarming. And yet there are other almost imperceptible changes - I am thinking of the exhaustion of our natural resources, and especially of soil erosion and these are perhaps more dangerous still, because once we begin to feel their repercussions it will be too late." (p144 of The Dalai Lama's Little Book of Inner Peace: 2002, Element Books, London) Soil - Where would we be without it? (Tell weathering, “Thanks!”) Splash Erosion Sheet Erosion Text Text In this clearcut, most of the vegetation has been stripped from surface of steep slopes in an area with very heavy rains. Severe erosion occurs in cases such as this, causing stream sedimentation and the loss of nutrient rich topsoil. Papua New Guinea 1990 2005 Soils that took over 10,000 years to form, are gone in > 10 years. Dead Zones - Related to Soil Erosion TROPICS & BAUXITE 15.7 kWh to produce 1 kg of virgin aluminum! 0.735 kWh to recycle 1 kg aluminum Ode to Feldspar! by Jeff Simpson! I like my house's kitchen.! It has a real big sink.! The sink is made of porcelain.! And the porcelain comes from feldspar. Tissue anybody? Weathering and Soil Objectives! ! Give specific examples how mechanical weathering works. ! Identify in images chemical weathering & explain the processes.! Describe why mechanical and chemical weathering rates vary. ! Identify erosional features and explain their cause.! features - spheroidal, balancing rocks, hoodoos, slopes, exfoliation domes, talus slopes Correlate particle size and weathering rate.! Give examples how CW affects minerals differently.! Identify which rocks are most succeptible to MW and CW.! Trace how soil develops and erodes. ! Explain where the best soils will occur and why.! Explain the effect of climate on soil.! Explain the consequences of soil erosion.! Be familiar with different soil types. ! !
